«

Hi,

I'm having problems retaining my dynamic columns during postbacks.
I've read that if you create dynamic columns at runtime, you have to
add them during the page_init event. I've done that, but I'm not sure
what else I'm supposed to do to make this work properly. Basically,
I've created a search page with a bunch of criteria - when the user
clicks search, it searches for all the criteria that has been filled
in and eventually stores whether a criterion is active or not in a
view state variable, then it should go through them and add a column
if the criterion is active. I've been playing around with different
things, but nothing makes my dynamic columns stay when I try to sort
or, more importantly, when I try to pull data from the dynamic
columns. I've added the function to the page_init event that adds all
the dynamic columns, but am I supposed to rebind the grid afterwards?
I may also be mismanaging my view state variables.

Thanks for any ideas or suggestions anyone can give me.

Code Follows - I tried to edit it down a bit:

<asp:datagrid id="dgdSearch" runat="server" BackColor="White"
Width="374px" Font-Names="verdana"
BorderColor="#3366CC" BorderStyle="None" Font-Size="X-Small"
AutoGenerateColumns="False" AllowPaging="True" PageSize="15"
AllowSorting="True"
CellPadding="4" BorderWidth="1px">
<SelectedItemStyle Font-Bold="True" ForeColor="#CCFF99"
BackColor="#009999"></SelectedItemStyle>
<AlternatingItemStyle BackColor="Gainsboro"></AlternatingItemStyle>
<ItemStyle ForeColor="#003399" BackColor="White"></ItemStyle>
<HeaderStyle Font-Bold="True" ForeColor="#CCCCFF"
BackColor="#003399"></HeaderStyle>
<FooterStyle ForeColor="#003399" BackColor="#99CCCC"></FooterStyle>
<Columns>
<asp:HyperLinkColumn Text="View" Target="_blank"
DataNavigateUrlField="PropertyID"
DataNavigateUrlFormatString="PropertyMain.aspx?Pro pertyID={0}"
DataTextField="PropertyID" SortExpression="PropertyID"
HeaderText="Property ID"></asp:HyperLinkColumn>
<asp:TemplateColumn HeaderText="Mark">
<ItemTemplate>
<asp:CheckBox id="chkMark" runat="server"></asp:CheckBox>
</ItemTemplate>
</asp:TemplateColumn>
<asp:ButtonColumn Visible="False" Text="Delete"
CommandName="Delete"></asp:ButtonColumn>
</Columns>
<PagerStyle HorizontalAlign="Left" ForeColor="#003399"
BackColor="#99CCCC" Mode="NumericPages"></PagerStyle>
</asp:datagrid>




Private Sub Page_Init(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Init
'CODEGEN: This method call is required by the Web Form
Designer
'Do not modify it using the code editor.
InitializeComponent()

Call AddDynamicColumns()

End Sub


Private Sub Page_Load(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Load
'Put user code to initialize the page here
txtUser.Text = Web.HttpContext.Current.User.Identity.Name

If Not Page.IsPostBack Then
FillDropDowns()
Me.btnAddNew.Attributes.Add("onClick",
"window.open('PropertyMain.aspx');")

' Create viewstates for the boolean variables
viewstate.Add("blnCounty", False)
viewstate.Add("blnPropertyType", False)
'** additional criteria items removed for brevity ***

End If

End Sub


Private Sub btnSearch_Click(ByVal sender As System.Object, ByVal e
As System.EventArgs) Handles btnSearch.Click

FillSearchDatagrid()

End Sub

Private Sub FillSearchDatagrid()

Dim lstItem As ListItem
Dim strSql As String
Dim intCount As Integer

Dim blnCounty As Boolean
Dim blnPropertyType as Boolean
'** additional criteria items removed for brevity ***

' Reset all the variables
strSQL = " WHERE 0 = 0"


' County
intCount = 0
For Each lstItem In lstCounty.Items
If lstItem.Selected Then
If Convert.ToInt32(lstItem.Value) > 0 Then
If intCount > 0 Then
strSql += " OR County = " & lstItem.Value
Else
strSql += " AND (County = " & lstItem.Value
End If
intCount = intCount + 1
blnCounty = True
End If
End If
Next
If intCount > 0 Then
strSql += ")"
End If
' Property Type
intCount = 0
For Each lstItem In lstPropertyType.Items
If lstItem.Selected Then
If Convert.ToInt32(lstItem.Value) > 0 Then
If intCount > 0 Then
strSql += " OR PropertyType = " &
lstItem.Value
Else
strSql += " AND (PropertyType = " &
lstItem.Value
End If
intCount = intCount + 1
blnPropertyType = True
End If
End If
Next
If intCount > 0 Then
strSql += ")"
End If

'*** additional criteria items removed for brevity ***

If viewstate("SearchString") Is Nothing Then
viewstate.Add("SearchString", strSql)
Else
viewstate("SearchString") = strSql
End If

Dim dsWeb As DataSet =
DAL.Properties.PropertiesSearchDataset(strSql, _
blnCounty)

'*** additional criteria items removed for brevity ***

Dim dvWeb As New DataView(dsWeb.Tables(0))

Dim strSort As String = ""

If Not viewstate("SortField") Is Nothing Then
strSort = Convert.ToString(viewstate("SortField")) &
Convert.ToString(viewstate("SortDirection"))
Else
strSort = "PropertyID"
End If

viewstate("blnCounty") = blnCounty
viewstate("blnPropertyType") = blnPropertyType
'*** additional criteria items removed for brevity ***

dvWeb.Sort = strSort
dgdSearch.DataSource = dvWeb
dgdSearch.DataKeyField = "PropertyID"
dgdSearch.DataBind()


End Sub

Private Sub dgdSearch_SortCommand(ByVal source As Object, ByVal e
As System.Web.UI.WebControls.DataGridSortCommandEvent Args) Handles
dgdSearch.SortCommand

If dgdSearch.EditItemIndex = -1 Then
' If SortDirection viewstate doesn't exist, add it
If viewstate("SortDirection") Is Nothing Then
viewstate.Add("SortDirection", " ASC")
End If
' If SortField viewstate doesn't exist, add it
If Convert.ToString(viewstate("SortField")) Is Nothing
Then
viewstate.Add("CustomSortField", e.SortExpression)
Else
' If SortField viewstate is the same as the sort
expression, then we
' just want to change direction
If Convert.ToString(viewstate("SortField")) =
e.SortExpression Then
If Convert.ToString(viewstate("SortDirection")) =
" ASC" Then
viewstate("SortDirection") = " DESC"
Else
viewstate("SortDirection") = " ASC"
End If
Else
' SortField viewstate is different than the sort
expression, we need
' to set new sortfield
viewstate("SortField") = e.SortExpression
viewstate("SortDirection") = " ASC"
End If
End If
FillSearchDatagrid()
End If

End Sub

Private Sub dgdSearch_PageIndexChanged(ByVal source As Object,
ByVal e As System.Web.UI.WebControls.DataGridPageChangedEvent Args)
Handles dgdSearch.PageIndexChanged

If dgdSearch.EditItemIndex = -1 Then
dgdSearch.CurrentPageIndex = e.NewPageIndex
FillSearchDatagrid()
End If
End Sub



Private Sub dgdSearch_ItemDataBound(ByVal sender As Object, ByVal
e As System.Web.UI.WebControls.DataGridItemEventArgs) Handles
dgdSearch.ItemDataBound

If e.Item.ItemType = ListItemType.Item Or e.Item.ItemType =
ListItemType.AlternatingItem Then
Dim webCtrl As WebControl
For Each webCtrl In e.Item.Controls
If CType(e.Item.Controls(2).Controls(0),
LinkButton).CommandName = "Delete" Then
CType(e.Item.Controls(2).Controls(0),
WebControl).Attributes.Add("onclick", "return confirm('Are you sure
you want to delete this item?');")
End If
Next
End If

End Sub

Private Sub dgdSearch_DeleteCommand(ByVal source As Object, ByVal
e As System.Web.UI.WebControls.DataGridCommandEventArgs ) Handles
dgdSearch.DeleteCommand

DAL.Properties.PropertiesDelete(Convert.ToInt32(dg dSearch.DataKeys(e.Item.ItemIndex)))
FillSearchDatagrid()

End Sub

Private Sub chkAllowDelete_CheckedChanged(ByVal sender As Object,
ByVal e As System.EventArgs) Handles chkAllowDelete.CheckedChanged

If Me.chkAllowDelete.Checked = True Then
Me.dgdSearch.Columns(2).Visible = True
Else
Me.dgdSearch.Columns(2).Visible = False
End If
FillSearchDatagrid()

End Sub

Sub AddDynamicColumns()


Dim bndCol4 As New BoundColumn
bndCol4.HeaderText = "Property Name"
bndCol4.DataField = "PropertyName"
bndCol4.SortExpression = "PropertyName"
dgdSearch.Columns.Add(bndCol4)

If Convert.ToBoolean(viewstate("blnPropertyType")) = True Then
Dim bndCol5 As New BoundColumn
bndCol5.HeaderText = "PropertyType"
bndCol5.DataField = "DescrPropertyType"
bndCol5.SortExpression = "DescrPropertyType"
dgdSearch.Columns.Add(bndCol5)
End If

If Convert.ToBoolean(viewstate("blnCounty")) = True Then
Dim bndCol8 As New BoundColumn
bndCol8.HeaderText = "County"
bndCol8.DataField = "DescrCounty"
bndCol8.SortExpression = "DescrCounty"
dgdSearch.Columns.Add(bndCol
End If
'*** additional criteria items removed for brevity ***

End Sub

I'm wondering if Denis Bauer's DynamicControlsPlaceholder control would help
you here?

"Problem:
ASP.NET gives a developer the opportunity to programmatically add controls
to a web form using ParentControl.Controls.Add(new Control());
However, these controls are not persisted in any way thus having to be
recreated for each subsequent request.

Goal:
To create a control that behaves like a placeholder but additionally handles
recreating dynamic controls on subsequent requests."

http://www.denisbauer.com/ASPNETCont...aceholder.aspx


"CAK" <ck-> wrote in message
news: om...
> Hi,
>
> I'm having problems retaining my dynamic columns during postbacks.
> I've read that if you create dynamic columns at runtime, you have to
> add them during the page_init event. I've done that, but I'm not sure
> what else I'm supposed to do to make this work properly. Basically,
> I've created a search page with a bunch of criteria - when the user
> clicks search, it searches for all the criteria that has been filled
> in and eventually stores whether a criterion is active or not in a
> view state variable, then it should go through them and add a column
> if the criterion is active. I've been playing around with different
> things, but nothing makes my dynamic columns stay when I try to sort
> or, more importantly, when I try to pull data from the dynamic
> columns. I've added the function to the page_init event that adds all
> the dynamic columns, but am I supposed to rebind the grid afterwards?
> I may also be mismanaging my view state variables.
>
> Thanks for any ideas or suggestions anyone can give me.
>
> Code Follows - I tried to edit it down a bit:
>
> <asp:datagrid id="dgdSearch" runat="server" BackColor="White"
> Width="374px" Font-Names="verdana"
> BorderColor="#3366CC" BorderStyle="None" Font-Size="X-Small"
> AutoGenerateColumns="False" AllowPaging="True" PageSize="15"
> AllowSorting="True"
> CellPadding="4" BorderWidth="1px">
> <SelectedItemStyle Font-Bold="True" ForeColor="#CCFF99"
> BackColor="#009999"></SelectedItemStyle>
> <AlternatingItemStyle BackColor="Gainsboro"></AlternatingItemStyle>
> <ItemStyle ForeColor="#003399" BackColor="White"></ItemStyle>
> <HeaderStyle Font-Bold="True" ForeColor="#CCCCFF"
> BackColor="#003399"></HeaderStyle>
> <FooterStyle ForeColor="#003399" BackColor="#99CCCC"></FooterStyle>
> <Columns>
> <asp:HyperLinkColumn Text="View" Target="_blank"
> DataNavigateUrlField="PropertyID"
> DataNavigateUrlFormatString="PropertyMain.aspx?Pro pertyID={0}"
> DataTextField="PropertyID" SortExpression="PropertyID"
> HeaderText="Property ID"></asp:HyperLinkColumn>
> <asp:TemplateColumn HeaderText="Mark">
> <ItemTemplate>
> <asp:CheckBox id="chkMark" runat="server"></asp:CheckBox>
> </ItemTemplate>
> </asp:TemplateColumn>
> <asp:ButtonColumn Visible="False" Text="Delete"
> CommandName="Delete"></asp:ButtonColumn>
> </Columns>
> <PagerStyle HorizontalAlign="Left" ForeColor="#003399"
> BackColor="#99CCCC" Mode="NumericPages"></PagerStyle>
> </asp:datagrid>
>
>
>
>
> Private Sub Page_Init(ByVal sender As System.Object, ByVal e As
> System.EventArgs) Handles MyBase.Init
> 'CODEGEN: This method call is required by the Web Form
> Designer
> 'Do not modify it using the code editor.
> InitializeComponent()
>
> Call AddDynamicColumns()
>
> End Sub
>
>
> Private Sub Page_Load(ByVal sender As System.Object, ByVal e As
> System.EventArgs) Handles MyBase.Load
> 'Put user code to initialize the page here
> txtUser.Text = Web.HttpContext.Current.User.Identity.Name
>
> If Not Page.IsPostBack Then
> FillDropDowns()
> Me.btnAddNew.Attributes.Add("onClick",
> "window.open('PropertyMain.aspx');")
>
> ' Create viewstates for the boolean variables
> viewstate.Add("blnCounty", False)
> viewstate.Add("blnPropertyType", False)
> '** additional criteria items removed for brevity ***
>
> End If
>
> End Sub
>
>
> Private Sub btnSearch_Click(ByVal sender As System.Object, ByVal e
> As System.EventArgs) Handles btnSearch.Click
>
> FillSearchDatagrid()
>
> End Sub
>
> Private Sub FillSearchDatagrid()
>
> Dim lstItem As ListItem
> Dim strSql As String
> Dim intCount As Integer
>
> Dim blnCounty As Boolean
> Dim blnPropertyType as Boolean
> '** additional criteria items removed for brevity ***
>
> ' Reset all the variables
> strSQL = " WHERE 0 = 0"
>
>
> ' County
> intCount = 0
> For Each lstItem In lstCounty.Items
> If lstItem.Selected Then
> If Convert.ToInt32(lstItem.Value) > 0 Then
> If intCount > 0 Then
> strSql += " OR County = " & lstItem.Value
> Else
> strSql += " AND (County = " & lstItem.Value
> End If
> intCount = intCount + 1
> blnCounty = True
> End If
> End If
> Next
> If intCount > 0 Then
> strSql += ")"
> End If
> ' Property Type
> intCount = 0
> For Each lstItem In lstPropertyType.Items
> If lstItem.Selected Then
> If Convert.ToInt32(lstItem.Value) > 0 Then
> If intCount > 0 Then
> strSql += " OR PropertyType = " &
> lstItem.Value
> Else
> strSql += " AND (PropertyType = " &
> lstItem.Value
> End If
> intCount = intCount + 1
> blnPropertyType = True
> End If
> End If
> Next
> If intCount > 0 Then
> strSql += ")"
> End If
>
> '*** additional criteria items removed for brevity ***
>
> If viewstate("SearchString") Is Nothing Then
> viewstate.Add("SearchString", strSql)
> Else
> viewstate("SearchString") = strSql
> End If
>
> Dim dsWeb As DataSet =
> DAL.Properties.PropertiesSearchDataset(strSql, _
> blnCounty)
>
> '*** additional criteria items removed for brevity ***
>
> Dim dvWeb As New DataView(dsWeb.Tables(0))
>
> Dim strSort As String = ""
>
> If Not viewstate("SortField") Is Nothing Then
> strSort = Convert.ToString(viewstate("SortField")) &
> Convert.ToString(viewstate("SortDirection"))
> Else
> strSort = "PropertyID"
> End If
>
> viewstate("blnCounty") = blnCounty
> viewstate("blnPropertyType") = blnPropertyType
> '*** additional criteria items removed for brevity ***
>
> dvWeb.Sort = strSort
> dgdSearch.DataSource = dvWeb
> dgdSearch.DataKeyField = "PropertyID"
> dgdSearch.DataBind()
>
>
> End Sub
>
> Private Sub dgdSearch_SortCommand(ByVal source As Object, ByVal e
> As System.Web.UI.WebControls.DataGridSortCommandEvent Args) Handles
> dgdSearch.SortCommand
>
> If dgdSearch.EditItemIndex = -1 Then
> ' If SortDirection viewstate doesn't exist, add it
> If viewstate("SortDirection") Is Nothing Then
> viewstate.Add("SortDirection", " ASC")
> End If
> ' If SortField viewstate doesn't exist, add it
> If Convert.ToString(viewstate("SortField")) Is Nothing
> Then
> viewstate.Add("CustomSortField", e.SortExpression)
> Else
> ' If SortField viewstate is the same as the sort
> expression, then we
> ' just want to change direction
> If Convert.ToString(viewstate("SortField")) =
> e.SortExpression Then
> If Convert.ToString(viewstate("SortDirection")) =
> " ASC" Then
> viewstate("SortDirection") = " DESC"
> Else
> viewstate("SortDirection") = " ASC"
> End If
> Else
> ' SortField viewstate is different than the sort
> expression, we need
> ' to set new sortfield
> viewstate("SortField") = e.SortExpression
> viewstate("SortDirection") = " ASC"
> End If
> End If
> FillSearchDatagrid()
> End If
>
> End Sub
>
> Private Sub dgdSearch_PageIndexChanged(ByVal source As Object,
> ByVal e As System.Web.UI.WebControls.DataGridPageChangedEvent Args)
> Handles dgdSearch.PageIndexChanged
>
> If dgdSearch.EditItemIndex = -1 Then
> dgdSearch.CurrentPageIndex = e.NewPageIndex
> FillSearchDatagrid()
> End If
> End Sub
>
>
>
> Private Sub dgdSearch_ItemDataBound(ByVal sender As Object, ByVal
> e As System.Web.UI.WebControls.DataGridItemEventArgs) Handles
> dgdSearch.ItemDataBound
>
> If e.Item.ItemType = ListItemType.Item Or e.Item.ItemType =
> ListItemType.AlternatingItem Then
> Dim webCtrl As WebControl
> For Each webCtrl In e.Item.Controls
> If CType(e.Item.Controls(2).Controls(0),
> LinkButton).CommandName = "Delete" Then
> CType(e.Item.Controls(2).Controls(0),
> WebControl).Attributes.Add("onclick", "return confirm('Are you sure
> you want to delete this item?');")
> End If
> Next
> End If
>
> End Sub
>
> Private Sub dgdSearch_DeleteCommand(ByVal source As Object, ByVal
> e As System.Web.UI.WebControls.DataGridCommandEventArgs ) Handles
> dgdSearch.DeleteCommand
>
>
> DAL.Properties.PropertiesDelete(Convert.ToInt32(dg dSearch.DataKeys(e.Item.ItemIndex)))
> FillSearchDatagrid()
>
> End Sub
>
> Private Sub chkAllowDelete_CheckedChanged(ByVal sender As Object,
> ByVal e As System.EventArgs) Handles chkAllowDelete.CheckedChanged
>
> If Me.chkAllowDelete.Checked = True Then
> Me.dgdSearch.Columns(2).Visible = True
> Else
> Me.dgdSearch.Columns(2).Visible = False
> End If
> FillSearchDatagrid()
>
> End Sub
>
> Sub AddDynamicColumns()
>
>
> Dim bndCol4 As New BoundColumn
> bndCol4.HeaderText = "Property Name"
> bndCol4.DataField = "PropertyName"
> bndCol4.SortExpression = "PropertyName"
> dgdSearch.Columns.Add(bndCol4)
>
> If Convert.ToBoolean(viewstate("blnPropertyType")) = True Then
> Dim bndCol5 As New BoundColumn
> bndCol5.HeaderText = "PropertyType"
> bndCol5.DataField = "DescrPropertyType"
> bndCol5.SortExpression = "DescrPropertyType"
> dgdSearch.Columns.Add(bndCol5)
> End If
>
> If Convert.ToBoolean(viewstate("blnCounty")) = True Then
> Dim bndCol8 As New BoundColumn
> bndCol8.HeaderText = "County"
> bndCol8.DataField = "DescrCounty"
> bndCol8.SortExpression = "DescrCounty"
> dgdSearch.Columns.Add(bndCol
> End If
> '*** additional criteria items removed for brevity ***
>
> End Sub